What AMP is
AMP is a web component framework with conventions intended to support efficient page delivery. It is a particular implementation approach, rather than a synonym for every fast mobile website.
Google says AMP itself is not a ranking factor. AMP pages are subject to the same quality and search requirements as other pages. Building an AMP version does not guarantee a search feature, better rankings or a passing Core Web Vitals result.
When the distinction matters
An existing publisher may need to maintain an AMP version and its relationship with a canonical page. Another website may meet its performance goals using a single responsive site. The choice should reflect the actual publishing and platform requirements.
If separate versions exist, they should provide equivalent essential information and working user journeys. Measurement, links and indexing signals also need to be checked when changing or retiring an implementation.
Measure the outcome
Review real user performance where data is available, alongside repeatable lab tests and the important interactions. The label attached to the framework does not establish whether a customer can read, navigate or complete an action efficiently.